The present invention relates to the generation of three-dimensional sound and, more particularly, to the creation of a new kind of sound which, unlike reverberatory or reflective echo effects, appears to have a three-dimensionality in space which does not depend upon reflection, which appears to move toward the listener and to rotate in space, rather than simply receding from the listener and which, in general, utilizes a unique space to create a three-dimensionality quite different from conventional decaying echo effects.
While there have been many efforts to create three-dimensional effects with sound, I have considered especially U.S. Pat. No. 5,337,363 dated Aug. 9, 1994, entitled METHOD FOR GENERATING THREE DIMENSIONAL SOUND, U.S. Pat. No. 4,817,149 issued Mar. 28, 1989 entitled THREE-DIMENSIONAL AUDITORY DISPLAY APPARATUS AND METHOD UTILIZING ENHANCED BIONIC EMULATION OF HUMAN BINAURAL SOUND LOCALIZATION, U.S. Pat. No. 5,487,113 issued Jan. 23, 1996 entitled METHOD AND APPARATUS FOR GENERATING AUDIOSPATIAL EFFECTS, U.S. Pat. No. 5,469,511 issued Nov. 21, 1995 entitled METHOD AND APPARATUS FOR PRESENTATION OF ON-LINE DIRECTIONAL SOUND and U.S. Pat. No. 4,731,848 issued Mar. 15, 1988 entitled SPATIAL REVERBERATOR.
These patents disclose various techniques for generating reverberation and echo effects.
Over the past three decades the sound production field has been searching for xe2x80x9ctrue three dimensionalxe2x80x9d sound. Although there have been amazing developments in sound production such as: digital time-delay effects, prologic surround sound and cinema, illusional, three-dimensional audio, true three-dimensional sound has remained undiscovered.
The failure to produce xe2x80x9ctrue three-dimensionalxe2x80x9d sound begins with the confusion among artists as to what is meant by a three-dimensional sound. Artists have believed sounds made in acoustical environments either natural such as tunnels or caves or man-made such as a concert hall or cathedral are truly three dimensional because of the sensations of depth and spaciousness. This belief led to the development of machines which mimicked those previously mentioned acoustical environments.
Other artists believed that relative to the listener""s position, sounds could appear to be moving from one location to another location such that a listener could follow the sound; such sound also have heretofore been treated as xe2x80x9ctrue three-dimensionalxe2x80x9d sound. By studying human sound localization, sound cues were developed which were to aid the listener is locating sounds in three-dimensional space. Such techniques as using templates, gray and while noise patterns, multiple microphones used to generate different arrival times to the human ears were employed to emulate human binaural sound localization discussed at length in Myers U.S. Pat. No. 4,817,149xe2x80x94xe2x80x9cTHREE-DIMENSIONAL AUDITORY DISPLAY APPARATUS AND METHOD UTILIZING ENHANCED BIONIC EMULATION OF HUMAN BINAURAL SOUND LOCALIZATIONxe2x80x9d. By focusing on directionality the artists needed to add three more loud speakers to the existing two speaker stereo system in order to expand the stereo image and fool the listener into believing that sounds were actually moving around.
Such beliefs, these being only a couple among the many, have shown that the concept of three dimensionality has been obscured. So to clear away the confusion about the definition of xe2x80x9cReal true three-dimensionalxe2x80x9d sound, I have posed two points of view. The logical view and the artistic view.
The logical view asks the question: What does it mean to be three dimensional?
The rule says: An object is considered three dimensional if it has a length, a width and a height of depth.
When this rule is applied to earth""s air space, one can see that air is not an object with a length, a width and a height or depth. So even through air can be used to do work, air itself is not three dimensional. This means, the movement of air molecules by emanating vibrations which produces what we call xe2x80x9csoundsxe2x80x9d is also not three dimensional.
So, from the logical point of view there is no such thing as a xe2x80x9cthree dimensionalxe2x80x9d sound. From this viewpoint it would appear that artists are searching for something that does not exist. If this viewpoint is true, then what is it that xe2x80x9cthree dimensionalxe2x80x9d sound requires?
From an artistic point of view, the rule here is: sound images must appear to have a length, a width and a height or depth so realistic that it causes the human being to experience responses or reactions to those images as if they were real.
Such experiences in visual space are for example:
Trying to grab an object in a three-dimensional picture or hologram.
Attempting to avoid an object such as a pitchfork being brought closer to the audience by a character in a three-dimensional motion picture or the fear one experiences when viewing roller coaster travel in virtual reality.
These experiences a human being feels when viewing three-dimensional imagery are all a part of the concept of Dimensionality.
Dimensionality only occurs when three dimensions of length, width and height or depth are in some kind of space. Without some kind of space these images would remain two dimensional. By this definition a film space allows images in motion pictures to appear three dimensional.
Artists searching for xe2x80x9ctrue three dimensionalxe2x80x9d sound should have taken a hint from the discovery of Cyberspace. If images on a computer screen can appear three dimensional due to cyberspace might there be an audio space where sounds can go and become three dimensional? If this question was asked, it would have become abundantly clear that these artists searching for xe2x80x9ctrue three dimensionalxe2x80x9d sound were using the wrong space. These artists are using Earth""s air space.
In this case the artists are using the logical view and are searching for something that does not exist. Without some kind of special space these artists are relying on trickery, stereophonic gimmickry and electronic wizardry in an attempt to fool listeners into believing the produced two-dimensional sound is actually three-dimensional sound.
It will therefore be a goal of my method to produce real, true, three dimensional sound contained inside a unique three-dimensional audio tape space thereby making the audio tape itself, the container.
It is, therefore, the principal object of the present invention to provide an improved method of producing a three-dimensional sound true to the effects described above and which, unlike the efforts previously used to improve depth perception in sound, is capable of generating a depth perception which is either nondirectional or multidirectional, does not depend on a reflective echo effect and is not characterized by damping, fading or decay of the echo.
Another object of this invention is to enhance sound so as to provide a recorded audio experience in which an originally recorded sound is greatly enhanced, especially by imparting an unusual three-dimensionality thereto.
It is also an object of the invention to make use of that unique space within the audio tape which has been alluded to previously. The audio space is not unique, what is unique ia a greater use of available space which stereo underuses. 3D exploits that space, by putting 4 sounds in the space.
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a method of recording and reproducing a sound which transcends the conventional stereophonic recording reverberation and echo-generating techniques by utilizing delays between rerecorded otherwise identical signals so that an echo is ultimately generated following multigenerational recording that does not decay or constitute a reverberation, but rather creates a rotation of the sound in the space reaching the listener and as a result of a unique exploitation of the tape space.
According to this invention, the original sound is binaurally recorded and the original stereo tape recording is duplicated. These two identical tapes are then played through respective players each of which has a right and left channel output and the four outputs are selectively combined by Y-connectors or Y-couplers (reverse splitters) in pairs to generate the right and left channel inputs to a tape recorder. The resulting tape is again duplicated and the two tapes which then result are played again with a time-delay while the right and left audio outputs of the players are combined through Y-connectors or reverse splitters, again in any pairing to provide right and left channel inputs for recording of the fifth tape. That fifth tape carries the final recorded sound with a so-called third echo or three dimensionality which is readily apparent when that tape is played through a conventional player with right and left channel outputs.
Of course the process can be continued and, for to example, the fifth tape may be duplicated and the fifth tape and its duplicate can be played as a further time delay to serve as an input to a recorder through reverse splitters or Y-couplers, in which case the seventh tape thus resulting will carry the three-dimensional effect.
The inputs to the recorder following duplication, can have its right and left channels receive inputs from reverse splitters each of which has both output channels of a respective recorder or one output channel of one player and an output channel from the other player.
In all cases, the result will be the three dimensionality described above.
According to the invention, the time delay between playing of the duplicates for each channel of recording with the time offset can be between say 25 ms and 0.99 s (990 ms) with preferred values of the delay xcex941 in the first generation between 100 ms and 500 ms and in the second generation delay xcex942 between 50 ms and 250 ms. The xcex941 and xcex942 may be the same or different. Preferably the delay xcex942 is shorter than the delay xcex941.
The method of the invention thus comprises the steps of:
(a) binaurally recording an initial sound to form a first recording;
(b) duplicating the first recording to form a first duplicate;
(c) playing the first recording and the first duplicate with a first time delay xcex941 there between with respective players each having right and left channel outputs;
(d) combining one of the channel outputs of each of the players in a respective Y connector for each of a right and a left channel input of a recorder to form a second recording;
(e) duplicating the second recording to form a second duplicate;
(f) playing the second recording and the second duplicate with a second time delay xcex942 therebetween with respective players each having right and left channel outputs; and
(g) combining one of the channel outputs of each of the players in step (f) in a respective Y connector for each of a right and a left channel input of a recorder to form a further recording carrying a three-dimensional sound signal.
In step (d) as described above, the right and left channel output of each player can be combined in a respective Y-connector to form a respective input of the recorder forming the second recording. Alternatively, the right and left channel outputs of each player may be combined with a right or left channel output of the other player in a respective Y-connector to form a respective input of the recorder forming the second recording. Similarly, in step (g), two channels outputs of each player can be combined in a Y-connector to a respective input of the recorder forming the further recording or a right channel output of one player and a channel output of the other player can be combined in a respective Y-connector to form an input for the further recording. The ability to select among outputs of the players in each case for the combination in respective Y-connectors as inputs for a subsequent recording, increases the versatility of the system of the invention.